As a full-tank regulation unit for performing full-tank regulation at the time of refueling a fuel tank of an automobile, a vent tube may be used. One end of the vent tube is inserted into the fuel tank so as to be opened therein, and the other end of the vent tube is connected to the vicinity of a fuel filling opening of a fuel filling pipe. During refueling, gas such as fuel vapor, air, etc. in the fuel tank is made to go out from the fuel filling opening through the vent tube. When the opening of the inserted one end of the vent tube is immersed in fuel within the fuel tank, the fuel climbs up the vent tube and the fuel filling pipe. And, when the climbing-up fuel contacts a sensor of a fuel filler gun inserted into the fuel filling opening, refueling is stopped.
An evaporant line for allowing gas to flow from the fuel tank toward a canister is provided, and the evaporant line is provided with a cut valve (roll-over valve) and a check valve. The cut valve drains gas in the fuel tank out to the canister when the internal pressure of the fuel tank increases to exceed a predetermined value, and introduces air into the fuel tank from the canister when the internal pressure of the fuel tank becomes negative.
Patent Literature 1 discloses, as such check valve, a valve which has a valve casing, a positive pressure valve, and a negative pressure valve. The valve casing has an opening portion which communicates with the cut valve and an opening portion which communicates with the canister. The positive pressure valve is disposed inside the valve casing, and an internal space of the positive pressure valve communicates with the cut valve and the canister. The positive pressure valve is urged to close the opening portion of the valve casing which communicates with the cut valve. The negative pressure valve is disposed within the positive pressure valve. The negative pressure valve is urged to close the canister-side opening portion in the positive pressure valve.
As another full-tank regulation unit for performing full-tank regulation at the time of refueling a fuel tank of an automobile, there is also used a full-tank regulation valve which is attached to an outlet for releasing gas in the fuel tank to the canister through an evaporant line. The full-tank regulation valve closes the outlet when the fuel level reaches a predetermined height. When the fuel level reaches the predetermined height at refueling time, since the outlet is closed by the full-tank regulation valve, the internal pressure of the fuel tank rapidly increases, and the fuel climbs up in the fuel filling pipe and contacts the sensor of the fuel filler gun inserted into the fuel filling opening. Thus, refueling is stopped.